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Construction Corner: Robotic fabricator could change how buildings are constructed

How often have you seen marketing messages that promise “to change forever the way you…” only to discover the message is the kind that gives marketing a bad name.

The more I see that promise, the more inclined I am to ignore it.

But I recently ran across an article about a robotic fabricator developed by Markus Giftthaler at the ETH Zurich, in Switzerland, which could, the headline said, "change the way" buildings are constructed.

Giftthaler is a serious scientist, not a marketer, so I read the piece.

Back in the 1970s, robots revolutionized the auto industry doing a wide range of jobs more reliably and quickly than humans. Before long people were touting robotics for use in construction.

But a construction site is a complex place posing unique problems, which is why fabrication of complex elements is sometimes done off-site.

What if those odd shapes and sizes could be fabricated right in the building where they will be used? Could a robot do that?

What Giftthaler and his team have done is develop a new class of robot, which they call In Situ Fabricator1.

The machine was designed from the bottom up to be practical. It can build stuff using a range of tools and do it with a precision of less than five millimetres. It is able to operate semi-autonomously in a complex, changing environment. It can reach the height of a standard wall. It can fit through ordinary doorways. It’s dustproof and waterproof. It runs off standard electricity and has battery backup. It’s also connected to the Internet so an architect can make real-time changes to plans if necessary.

The machine has a set of cameras to sense its environment and on-board processors for navigating and planning tasks. It has a flexible, powerful robotic arm so it can handle construction tools, even in awkward spots.

The researchers have used their invention to build two structures at an experimental construction site in Switzerland called NEST.

The first was a double-leaf undulating brick wall 6.5 metres long and two metres high, and made of 1,600 bricks. Positioning such a wall correctly on a construction site can be tricky. But the robot made a map of the site with information gathered from its sensors, then compared it with the architect’s plans. Then, with the desired location and orientation pinpointed, it built the wall. Nice.

The second job it tackled was welding wires together to form a complex, curved steel mesh that can be filled with concrete.

Welding creates tensions that can change the shape of the structure in unpredictable ways. But the robot was able to assess the structure and allow for any shape changes as it welded the next set of wires together. Impressive.

But the machine is not perfect. For example, it weighs almost 1.5 tonnes, making it too heavy to enter many standard buildings.

It also needs to be able to handle heavier objects. This first machine is capable of manipulating things that weigh up to about 40 kilograms. Somewhere around 60 kilos would be better. But its electric motors are unable to handle heavier objects with the same level of precision. As well, the motors are unreliable in the conditions often found on construction sites.

In Situ Fabricator1 is useful for what researchers call "proof of concept." Now the team is working on In Situ Fabricator2.

It has already designed and built a hydraulic actuator capable of controlling a next-generation robot arm that can handle heavier objects more reliably. They’re still working on the weight problem, hoping to reduce it by two-thirds to 500 kilos.

That is likely to take the rest of this year. And who knows, it might really be the machine that changes the way buildings are constructed.